1. Field of the Invention
The invention is directed to a device for drawing in material webs, preferably paper webs, through a drier which is arranged downstream of a web-fed rotary printing machine. The web is drawn by means of a draw-in member comprising a draw-in tip and a power transmission for transmitting force from a drive to the draw-in tip and from the draw tip to the start of the material web, wherein the power transmission runs inside a guide.
2. Description of the Prior Art
Driers in which the material web, i.e. a printing stock web, in particular a web of paper, is dried are often arranged downstream of web-fed rotary printing presses. At temperatures of up to 300.degree. C., the volatile components of the printing inks evaporate. A drier of this type in which hot air is blown out of an oven via chambers and pipes against the printing stock web from both sides is known from U.S. Pat. No. 4,341,024.
On the other hand, it is already known to reintroduce a printing stock web into a web-fed rotary printing machine by means of a draw-in device. It is likewise already known to draw the printing stock web not only through the printing machine, but also through a drier arranged downstream thereof. The draw-in device has a draw-in member for drawing in the printing stock web. The draw-in member has a power transmission and a draw-in tip fastened thereto, to which tip the start of the printing stock web is fastened. The power transmission, e.g. a cable or roller chain, is acted upon by drive means, e.g. a driving wheel, via frictional engagement (a cable) or positive engagement (a roller chain) and transmits this force to the draw-in tip. When the power transmission runs through the guide and also through the drier, the following problem arises. After the power transmission has been withdrawn from the guide at the conclusion of the drawing in process and the printing machine is put into operation and while the printing stock web carrying wet printing ink is being dried in the drier, the guide located in the drier is soiled by condensing components of the volatile substances of the printing ink and becomes clogged. In view of this, the power transmission can no longer be relied upon in every case to draw a new web of printing stock into the guide. The power transmission is either substantially slowed down by dirt and thus exposed to a high level of wear or it can no longer be moved in the guide at all.